Innovative Surface Logging Solution Provides Integration of Rock and Fluid Data
Mario Chiaramonte is Chief Technology Officer at Milan-based GEOLOG Surface Logging. JPT asked him about his company’s recent data-integration-technology platform and how it can affect reservoir characterization.
|Integrated, High-Resolution Reservoir Description|
GEOLOG has long specialized in rock and fluid characterization. When did it begin to develop its advanced-surface-logging (ASL) solution?
Development of leading-edge technologies is an important part of our strategy. Eight years ago, we began to focus on innovative technologies for fluid characterization. The first that we introduced was the DualFidStar technology, an instrument developed in house that was able to analyze light hydrocarbons up to C8 every 120 to 150 seconds depending on the requested resolution.
Two years later, we performed isotopic analyses from C1 to C3 at the rig site thanks to another instrument developed in house. We then began to perform elemental and mineralogical analyses on rock samples at the rig site. That has led us to the developments of the last 3 years, in which we began to combine rock and fluid data to acquire an integrated, high-resolution reservoir description.
Who do you see as the primary target for this technology? How might it change their operations?
Historically, ASL was only focused on supporting key decisions during well construction, and subsurface geologists were our main interface. Now, however, the technology is producing a wide range of data useful in any phase of exploration and of development.
For example, development projects are based on data acquired during the exploration and appraisal phases, but during field development, ASL can acquire a lot of additional data of good quality in real time while drilling and at low cost.
This data can be used to refine the development model, to clarify uncertainties, and to avoid repeating the same errors in different wells. ASL can therefore be crucial to progressively improve reservoir knowledge well after well, increasing future production and recovery factor.
What makes ASL unique as a solution set?
ASL provides integrated, detailed, fast, low-cost data for faster and more-informed decision making. Our clients see the considerable advantages of the possibility of obtaining large amounts of good-quality data at low cost and integrating them to obtain a comprehensive characterization of the reservoir.
Furthermore, the data are obtained in a short period of time, without the long lead time usually spent waiting on expensive laboratory results. ASL is performing direct and different measurements on the same sample by use of different technologies. This unique approach allows for a true integration of different data sets. A high-resolution reservoir characterization is therefore obtainable thanks to the low cost of single analyses and the possibility of customizing sampling intervals as a function of the results obtained in real time.
How were you initially positioned in the market for introduction of ASL?
Over the last 15 years, our company grew rapidly, evolving from a domestic to an international service company operating in more than 50 countries. Our growth was supported by a continuous and fast improvement of proprietary technologies. In particular, we were one of the first companies to introduce ASL services, and have since continuously contributed to the improvement of this technological area.
Can you briefly discuss some of the geochemical tools that play a notable role in ASL?
Our company is gradually and effectively bringing a sophisticated geochemical laboratory to the wellsite. This has been possible thanks not only to our proprietary research-and-development efforts, but also to the exploitation of opportunities arising from impressive progresses in analytical chemistry. Examples of GEOLOG’s geochemical applications at the wellsite include carbon stable isotope analyses and thermal extraction gas chromatography (GC).
We were the first company to introduce a complete set of isotopic analyses from C1 up to C3 in 2011. The latter services have been requested and applied in many different basins and geological contexts, allowing us to acquire great experience in data acquisition, but, more importantly, data interpretation.
Isotopes can provide many different types of information well beyond the simple distinction between thermogenic and biogenic gas.
Isotopic data can be used to understand
Maturity of the gas
Mixing of different gas types
Presence of permeability barriers
Isotopic composition can also highlight the presence of artefacts in mud gas owing to bit wearing. Studies are also in progress to use isotopes to distinguish different permeability zones in the reservoir.
Thermal extraction GC is a well-known laboratory technique that we have recently moved to the well site. This relatively simple methodology, thermally extracting hydrocarbons from cuttings, is a powerful tool to characterize different types of oil or oil property changes in the reservoir while drilling. In addition, it can provide useful indications about oil/water contacts.
All these data can have a huge impact on completion strategies, future recovery factor, and quality of produced hydrocarbons. An example of this important application is West Africa, where detecting the presence of biodegraded heavy oils is of vital importance.
What are some of the challenges in traditional approaches to collection of samples, and how does your company’s technology approach some of these challenges?
All the analyses performed at the wellsite are based on two types of samples: gas extracted from mud, and cuttings. In both cases, there are some challenges to overcome to obtain representative samples.
Mud gas extraction is a complex operation; reproducibility and repeatability are a must, and a quantitative assessment of gas in the mud is required. All this must be performed continuously while drilling. Our company has developed its own device for mud-gas extraction based not only on its own experimental tests and experience, but also on numerical simulations of the extraction process performed in cooperation with the prestigious Politecnico di Milano. We recently patented a new and accurate approach to evaluate mud-extraction efficiency.
As for cuttings, in addition to sophisticated proprietary software for lag-time calculation, we developed methodologies based on natural gamma ray measurements on cuttings to control their estimated original depth by matching the experimental results to gamma ray logs obtained during measurement-while-drilling or logging-while-drilling operations. Specific methodologies were also set up to clean samples from mud contaminations and to select cuttings for analyses on the basis of their grain size.
What is RICH, and how is it related to ASL?
RICH, reservoir integrated characterization, is the result of the deep integration of all the data acquired at the wellsite that describe the properties of fluids and rocks. The reservoir is often studied as a geological formation, looking at rock properties, whereas other analyses concentrate on fluid-property characterization. Integration of these two types of data is only performed by reservoir specialists at the last stage of the process, and in some cases, it is not performed at all.
“RICH represents the early integration of all available reservoir data, concurrently studying heterogeneities of fluids and rocks, putting everything in the same context.
An additional advantage of RICH is the number of available data (lower costs than those of laboratory analyses generally means more data) and the flexibility to acquire more samples where higher resolution is needed, thanks to the availability of real-time results.
Can you briefly discuss the GEOLOG Foundation?
The GEOLOG Foundation encompasses our efforts in giving something back to the communities in which we work around the world. We operate in over 45 countries and, unfortunately, many of these nations suffer from underdevelopment or social inequality issues. Through the Foundation, we support and promote local charities, mostly focusing on the education and quality of life of young children, but also providing assistance in other areas such as hospitals and disaster-relief efforts. An example of this is our ongoing support for the Institute Don Bosco in Luanda, Angola. This non-profit institute run by priests daily provides free schooling, including specialized technical courses, and food to over 8,000 children in and around Luanda from kindergarten all the way to high school.
An important aspect of the Foundation is that we do not make impersonal monetary contributions to charities; instead, our staff is personally involved in charity and social activities, such as organizing events, providing entertainment for children in hospitals, refurbishing orphanages.
Innovative Surface Logging Solution Provides Integration of Rock and Fluid Data
Chris Carpenter, JPT Technology Editor
21 September 2017
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